General Hydroponics Dual Diaphragm air pump is the only air pump in the world that is manufactured exclusively for use with hydroponic systems. This high output pump (320 gph/ 20 Liters/minute capacity) has four adjustable 1/4” output valves that can be split off twice to power up to sixteen WaterFarm units. In addition, growers who use our Dual Diaphragm air pump can count on it to reliably oxygenate their reservoir with air stones.